Oil-less pressure relief valves

Abstract

A self contained one-way pressure relief valve for application to product packaging that does not require the addition of a sealing lubricant. Atop a base with an opening extending through the base is an adhesive-like material layer, and a dry strap of a silicone or other release film coated membrane, all of which are of gas impervious materials. The release film coated material layer covers the opening with the release film in contact with the adhesive-like material creating a surface attraction between the release film and the adhesive-like material. An intermediate layer of gas impervious material with an opening extending through such layer may be provided. A gas pervious filter material layer may be provided to block passage of fine particulates or liquid.

What is claimed as new and desired to be secured by Letters Patent is: 
     
       1. A one-way pressure relief valve for application to a closed package having an exterior surface and a gas-producing product therein, the valve comprising:
 a gas-impervious base layer having an outer edge, a top, a bottom, adhesive on the bottom for affixing the valve to the package exterior surface and a gas-flow opening extending entirely through the base layer from the bottom to the top; 
 a gas-impervious flexible cover over the base layer and the gas-flow opening; and 
 a pair of contacting and separable gas-impervious layers, one of the separable layers being associated with the base layer completely around the gas-flow opening and the other of the separable layers being associated with the flexible cover completely covering the gas-flow opening, the separable layers being of materials having material properties which keep the separable layers in contact to block passage of gas therebetween until a force from gas entering the gas-flow opening separates the layer associated with the flexible cover from the layer associated with the base layer sufficiently to allow the gas to flow between the separable layers, to the outer edge of the base layer, and out of the valve. 
 
     
     
       2. The valve of  claim 1  wherein the material properties of the separable layers provide an attraction between the separable layers thereby keeping the separable layers in contact. 
     
     
       3. The valve of  claim 1  wherein the material properties of the separable layers keep the separable layers in contact without a sealing lubricant. 
     
     
       4. The valve of  claim 1  wherein the layer associated with the flexible cover separates from the layer associated with the base layer at a gas pressure of less than 0.4 psig. 
     
     
       5. The valve of  claim 1  wherein one of the separable layers is of a self-wetting adhesive material. 
     
     
       6. The valve of  claim 5  wherein the other of the separable layers is of a silicone material or a dry release material. 
     
     
       7. The valve of  claim 6  wherein the self-wetting adhesive material is atop the base layer and the silicone material or dry release material is supported by the flexible cover. 
     
     
       8. The valve of  claim 1  further including a gas-impervious membrane supported by the flexible cover and the one of the separable layers associated with the flexible cover completely covering the gas-flow opening is on the gas-impervious membrane facing the other of the separable layers. 
     
     
       9. The valve of  claim 8  wherein the flexible cover has outer regions attached to the base layer and a flexible region therebetween supporting the gas-impervious membrane and the separable layer thereon. 
     
     
       10. The valve of  claim 1  further including a filter element which blocks passage of solid particulates between the separable layers. 
     
     
       11. The valve of  claim 10  wherein the filter element blocks passage of liquid and permits passage of the gas. 
     
     
       12. The valve of  claim 11  wherein the filter element is of a material selected from the group consisting of expanded polytetrafluoroethelene, a hydrophobic material and an oleophobic material. 
     
     
       13. The valve of  claim 1  in combination with the closed package to which the valve is attached. 
     
     
       14. A one-way pressure relief valve for application to a closed package having an exterior surface and a gas-producing product therein, the valve comprising:
 a gas-impervious base layer having an outer edge, a top, a bottom, adhesive on the bottom for affixing the valve to the package exterior surface and a gas-flow opening extending entirely through the base layer from the bottom to the top; 
 a gas-impervious flexible cover over the base layer and the gas-flow opening; 
 a gas-impervious intermediate layer between the base layer and flexible cover layer and having an outer edge, a top, a bottom, and a gas-flow opening in communication with the base layer gas-flow opening and extending entirely through the intermediate layer from the bottom to the top; and 
 a pair of contacting and separable gas-impervious layers, one of the separable layers being associated with the intermediate layer completely around the intermediate layer gas-flow opening and the other of the separable layers being associated with the flexible cover completely covering the intermediate layer gas-flow opening, the separable layers being of materials having material properties which keep the separable layers in contact to block passage of gas therebetween until a force from gas entering the gas-flow openings separates the layer associated with the flexible cover from the layer associated with the intermediate layer sufficiently to allow the gas to flow between the separable layers, to the outer edge of the intermediate layer, and out of the valve. 
 
     
     
       15. The valve of  claim 14  wherein the material properties of the separable layers provide an attraction between the separable layers thereby keeping the separable layers in contact. 
     
     
       16. The valve of  claim 14  wherein one of the separable layers is of a self-wetting adhesive material. 
     
     
       17. The valve of  claim 16  wherein the other of the separable layers is of a silicone material or a dry release material. 
     
     
       18. The valve of  claim 17  wherein the self-wetting adhesive material is atop the intermediate layer and the silicone material or dry release material is supported by the flexible cover. 
     
     
       19. The valve of  claim 14  further including a gas-impervious membrane supported by the flexible cover and the one of the separable layers associated with the flexible cover completely covering the gas-flow opening is on the gas-impervious membrane facing the other of the separable layers. 
     
     
       20. The valve of  claim 19  wherein the flexible cover has outer regions attached to the intermediate layer and a flexible region therebetween supporting the gas-impervious membrane and the separable layer thereon. 
     
     
       21. The valve of  claim 20  further including a filter element which blocks passage of solid particulates between the separable layers. 
     
     
       22. The valve of  claim 21  wherein the filter element blocks passage of liquid and permits passage of the gas. 
     
     
       23. The valve of  claim 22  wherein the filter element is of a material selected from the group consisting of expanded polytetrafluoroethelene, a hydrophobic material and an oleophobic material.